A quick coupler is fixed to an arm of a machine for connecting and disconnecting implements to the arm. For example, a quick coupler can be attached to the arm of a machine such as a backhoe or an excavator to connect and disconnect the arm and implements such as buckets, hammers, rippers, and grapples. Such quick couplers are advantageous because they allow a machine operator to change quickly from one implement to another. Thus, the use of a quick coupler makes the machine more efficient and versatile.
Several different types of quick couplers have been employed in the past. One exemplary quick coupler is disclosed in international patent application publication number WO2011/033253, which discloses a fully automatic coupler for an excavator arm. The coupler disclosed in WO2011/033253 includes a pair of jaws configured to receive corresponding pins on an implement. Each of the jaws is coupled to a corresponding latch mechanism. The first latching mechanism is configured to move to a closed or latched position when the coupler is in its normal configuration, and move to an open or unlatched position when the coupler is inverted. The second latch mechanism is connected to a hydraulic actuator configured to open and close the second jaw.
One shortcoming of having a hydraulic actuator controlling a jaw of the coupler is that should the actuator fail, the jaw could then open unexpectedly, causing the implement pins to become disconnected from the coupler. The present disclosure presents a quick coupler including an over-center locking system to position the jaws from an open position to a closed position and to retain the jaws in the closed position. In the closed position, the linkages in the locking system, are configured so that linkages resist further movement, thereby retaining the jaws in the closed position. An actuator may be provided to engage and disengage the locking system. However, because the actuator is placed outside of the load path between the implement and the quick coupler frame, the actuator need not be sized to withstand the implement load and the likelihood of disengagement is reduced over prior designs.